They are very different from FG's. Mainly because the tactic of play and the idea behind the decks is completely gone. The random cards pretty much make them walk-overs.
What should be different is the way the cards spin. My suggestion is 2 spins with unupgraded cards only and 1 spin with upgraded cards. This way you prevent upgraded and unupgraded cards ruining spins.
It's the rewards that should be better, not the half-bloods difficulty that should be adjusted.
Unless it was made clear that it works like that we would get so many "AI5 spins are fixed" threads and stuff like that. "only on the 3rd spin do you have a chance of winning a upgraded card"
Then people would want more ( as people do ) and demand all 3 spins give us a chance or something crazy like that.
Ok this comment is part joke part for real, but you know what I mean.
The only question to any increase in reward to halfboods is " will AI 6 be worth it anymore?". I feel like a player should be able to play AI5 as a stepping stone with little reward to AI 6. Finding the balance is hard but right now I think things are about right. I fight in PvP 1 and 2 alot. I talk and sometimes they say how far they are. Some that dont even know of the forums found a way or 2 of farming halfbloods, where falsegods you almost certainly need forum help to exspand your mind first. So the fact that halfbloods can be beaten without forum help and it will give some fair reward means that they are near balanced or they ARE balanced right now. EM firestall for example only needs like 4-6 upgrades and AI 5 farming is very worth while and simple. ( maybe a little hard to master but simple to pick up basics. ) Then fractal devourer and mono darkness are always decks that people see and copy and play against AI 5 and they win alot.